I performed heating maintenance today on two Carrier furnaces. Upon arrival, I noticed that the upstairs furnace was short cycling on heating mode. I tested all electrical components for both systems and they tested in range with no signs of damage. The temperature rise for the upstairs unit is 80° which is above the manufacturers rating. This is causing the high limit switch to trip and turn the system off in order to start up again shortly after. This means the system is overheating due to an air restriction. The static pressure (air flow blood pressure) is also over the manufacturers rating. Both systems blower wheel, evaporator coil, return air filters are clean and all vents are open. This means that the system is trying to operate with undersized ductwork. I will be following up on Monday to check the availability of both homeowners to receive a quote for ductwork from one of our comfort advisors. Also, the outlet for the upstairs furnace was sparking during operation. This is a
